From 08322ab8e166b00671a5f1c608e756a5690ab5cb Mon Sep 17 00:00:00 2001
From: Andreas Kling <awesomekling@gmail.com>
Date: Sun, 10 Feb 2019 14:46:43 +0100
Subject: [PATCH] LibGUI: Coalesce update rects at the GWindow level.

---
 LibGUI/GWidget.cpp | 6 ------
 LibGUI/GWidget.h   | 2 --
 LibGUI/GWindow.cpp | 9 +++++++++
 LibGUI/GWindow.h   | 1 +
 4 files changed, 10 insertions(+), 8 deletions(-)

diff --git a/LibGUI/GWidget.cpp b/LibGUI/GWidget.cpp
index 75f394188a..9d05141f3d 100644
--- a/LibGUI/GWidget.cpp
+++ b/LibGUI/GWidget.cpp
@@ -38,7 +38,6 @@ void GWidget::event(GEvent& event)
 {
     switch (event.type()) {
     case GEvent::Paint:
-        m_pending_paint_event_rects.clear();
         return handle_paint_event(static_cast<GPaintEvent&>(event));
     case GEvent::Resize:
         return handle_resize_event(static_cast<GResizeEvent&>(event));
@@ -175,11 +174,6 @@ void GWidget::update(const Rect& rect)
     auto* w = window();
     if (!w)
         return;
-    for (auto& pending_rect : m_pending_paint_event_rects) {
-        if (pending_rect.contains(rect))
-            return;
-    }
-    m_pending_paint_event_rects.append(rect);
     w->update(rect.translated(window_relative_rect().location()));
 }
 
diff --git a/LibGUI/GWidget.h b/LibGUI/GWidget.h
index ad45fa92d4..5b5cb957d5 100644
--- a/LibGUI/GWidget.h
+++ b/LibGUI/GWidget.h
@@ -136,7 +136,5 @@ private:
     SizePolicy m_vertical_size_policy { SizePolicy::Fill };
     Size m_preferred_size;
 
-    Vector<Rect> m_pending_paint_event_rects;
-
     bool m_fill_with_background_color { true };
 };
diff --git a/LibGUI/GWindow.cpp b/LibGUI/GWindow.cpp
index f9a76295ce..9fb21d61b5 100644
--- a/LibGUI/GWindow.cpp
+++ b/LibGUI/GWindow.cpp
@@ -147,6 +147,7 @@ void GWindow::event(GEvent& event)
     }
 
     if (event.is_paint_event()) {
+        m_pending_paint_event_rects.clear();
         if (!m_main_widget)
             return;
         auto& paint_event = static_cast<GPaintEvent&>(event);
@@ -196,6 +197,14 @@ void GWindow::update(const Rect& a_rect)
 {
     if (!m_window_id)
         return;
+    for (auto& pending_rect : m_pending_paint_event_rects) {
+        if (pending_rect.contains(a_rect)) {
+            dbgprintf("Ignoring %s since it's contained by pending rect %s\n", a_rect.to_string().characters(), pending_rect.to_string().characters());
+            return;
+        }
+    }
+    m_pending_paint_event_rects.append(a_rect);
+
     GUI_Rect rect = a_rect;
     int rc = gui_invalidate_window(m_window_id, a_rect.is_null() ? nullptr : &rect);
     ASSERT(rc == 0);
diff --git a/LibGUI/GWindow.h b/LibGUI/GWindow.h
index e7c406d8fe..f7d82e1bfd 100644
--- a/LibGUI/GWindow.h
+++ b/LibGUI/GWindow.h
@@ -69,6 +69,7 @@ private:
     WeakPtr<GWidget> m_global_cursor_tracking_widget;
     Rect m_rect_when_windowless;
     String m_title_when_windowless;
+    Vector<Rect> m_pending_paint_event_rects;
     bool m_should_exit_app_on_close { false };
 };